Various solenoid designs have been used in the automotive industry, including those for use in conjunction with automatic transmission systems. For example, automatic transmission control systems generally employ solenoids in order to control the pressure and flow of the transmission fluid. In this manner, the control of transmission fluid pressure can be used to engage and disengage a transmission clutch in response to an electrical input signal supplied to the solenoid, or the control of transmission fluid pressure can be used to maintain transmission line pressure.
Generally, solenoids employ a solenoid control valve to aid in the regulation of the fluid flow by the solenoid. An example of a solenoid control valve can be found in U.S. Pat. No. 4,998,559 to McAuliffe et al., the entire specification of which is incorporated herein by reference. Recently, the use of pulse width modulated solenoids has become more prevalent in certain automotive applications.
Although pulse width modulated conventional solenoid control valves have been somewhat successful in meeting the demands of the automotive industry, these pulse width modulated solenoid control valves can be further improved upon, e.g., in the areas of cost, quality, performance, and the like.
Accordingly, there exists a need for new and improved pulse width modulated solenoid control valves.